Controlled iteration order for interfaces #7609
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@wardi, it's ready for review |
| @@ -124,7 +124,7 @@ def get_user_from_token(token: str, | |||
| # do preprocessing in reverse order, allowing onion-like | |||
| # "unwrapping" of the data, added during postprocessing, when | |||
| # token was created | |||
| for plugin in _get_plugins(): | |||
| for plugin in reversed(list(_get_plugins())): | |||
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Why is this one back to reversing the old way?
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There are two sides to processing API tokens. When it's created and encoded into a string, all plugins can add additional properties to the token or modify existing properties. When the application receives the token, it decodes the token from a string and extracts all the properties. It sounds like a middleware for an API token, that's why data extraction should happen in reverse order compared to data injection.
This line used reversed originally, but I misinterpret it and set reverse_order to the whole interface. After additional checks(in order to add a comment with the reason behind the reverse order for the interface), I realized, that this interface has 4 methods and 3 of them are executed in normal order and only data extraction from the token received from user happens in reverse order. That's why I restored APIToken to its original form.
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Great, can you add the reason that the reversed plugin order can't be used here to the comment above?
Add
ckan_reverse_iteration_orderflag to the Interface class. Whenever it is set toTrue,PluginImplementationswill return plugins implementing this interface in reverse order.It reduces the risk of writing code where iteration goes not in the expected order. In addition, it makes more explicit, which interfaces are iterated in reverse order.
Finally(but I'd rather not mention it in the docs), it allows you to write
IActions.ckan_reverse_iteration_order = Truein order to revert the order of plugins during action registration(just an example, of course, you can do it with any interface). It may save someone who wants to patch things locally if we decide to change the order for a particular interface in the future or discover, that order was non-intentionally changedInterfaces that are traversed in reverse order: